The present invention relates to a titanium hydroxide, a photocatalyst produced from the titanium hydroxide and a photocatalytic coating agent. Specifically, a titanium hydroxide that may be utilized as a raw material for producing a photocatalyst which exhibits a superior photocatalytic activity by irradiation of visible light, a photocatalyst produced from the titanium hydroxide and a photocatalytic coating agent comprising the titanium hydroxide.
It has been researched that organic materials in water or NOx in air is decomposed and removed by a photocatalytic activity of photocatalyst such as a specific titanium oxide. In these days, it has been attracting an attention of researchers to decompose and remove such things using visible light as a light source in the point of general purpose and usage and it has been desired to develop a photocatalyst which exhibits a superior photocatalytic activity by irradiation of visible light.
Heretofore, the photocatalyst has been produced by calcining a titanium hydroxide, which may be commercially available. However, there are problems such that the photocatalyst obtained by calcining the commercially available titanium hydroxide in a commonly used way does not show a sufficiently high photocatalytic activity by irradiation of visible light.
One of the objects of the present invention is to provide a titanium hydroxide, which may be utilized as a raw material for producing a photocatalyst which exhibits a sufficiently high photocatalytic activity by irradiation of visible light. Other objects of the present invention are to provide a photocatalyst produced from the titanium hydroxide and to provide a photocatalytic coating agent comprising the photocatalyst.
The present inventors have undertaken extensive studies on such a titanium hydroxide. As a result, the present inventors have found that a titanium hydroxide having a specific amount of nitrogen content may be utilized as the raw material for producing a photocatalyst which exhibits a sufficiently high photocatalytic activity by irradiation of visible light, and a photocatalytic coating agent as well as such a photocatalyst may be easily produced from the titanium hydroxide, thereby the present invention has been accomplished.
The present invention first provides a titanium hydroxide having a nitrogen content of 2.3% by weight or more in terms of nitrogen atom based on the titanium hydroxide and/or having a nitrogen content of about 3.3% by weight or more in terms of nitrogen atom based on the titanium oxide obtained after calcining the titanium hydroxide in air at about 400xc2x0 C.
Secondly, the present invention provides a photocatalyst produced by calcining the above-described titanium hydroxide.
Thirdly, the present invention provides a photocatalytic coating agent comprising the above-described titanium hydroxide and a solvent.